1. Field of the Invention
The present invention relates to an image recording apparatus and an inkjet apparatus for double-side recording, and more particularly, to an image recording apparatus which seeks to stabilize ejection from an ejection head that ejects ink in a horizontal direction, and to an inkjet apparatus for double-side recording which can perform double-side recording by using this image recording apparatus, onto a rigid plate-shaped recording medium which is hard, heavy, and unbendable.
2. Description of the Related Art
In general, an inkjet recording apparatus (inkjet printer) that includes an inkjet head having an arrangement of a plurality of nozzles for ejecting ink, is known. Such an inkjet recording apparatus forms images on a recording medium by ejecting ink from the nozzles while causing the inkjet head and the recording medium to move relatively to each other.
Many inkjet recording apparatuses of this kind record images only on one side of a recording medium. However, inkjet recording apparatuses capable of double-side recording are demanded because of saving recording media or other reasons.
In view of such circumstances, various inkjet recording apparatuses for double-side recording have been proposed, which are capable of recording onto both sides of a recording medium that is a flexible medium, such as paper, resin sheet, cloth, or the like.
For example, Japanese Patent Application Publication No. 2003-182094 discloses an apparatus in which one or a plurality of recording heads are disposed on each side of a recording medium, the recording heads facing the sides of the recording medium. The recording heads can substantially simultaneously print on both sides of the recording medium, and images can be substantially simultaneously printed onto both recording surfaces of the recording medium, in a sequence of operations. In this way, the recording time can be shortened and the apparatus can be reduced in size.
Furthermore, Japanese Patent Application Publication No. 2004-181871 discloses an apparatus that has a recording medium reversal mechanism for recording on both sides of a medium. In this apparatus, after recording on one side of the medium, the recording medium is reversed with respect to the recording surface by means of the reversal mechanism, the medium is then conveyed while the recording medium is kept to faces the ejection openings of the recording head, and then recording is performed on the other surface of the recording medium. In this way, double-side recording and high-speed recording can be achieved.
Moreover, for example, Japanese Patent Application Publication No. 2004-216680 discloses an apparatus in which two rotating drums provided with recording heads are disposed in series on a conveyance path of a recording medium. In this apparatus, firstly, the recording medium is wound up onto the first rotating drum and recording is performed on one surface of the recording medium, whereupon the recording medium is wound up onto the second rotating drum and recording is performed on the other surface of the recording medium, so that images are recorded onto both sides of the recording medium. In this way, double-side recording can be achieved at high-speed by means of the compact apparatus.
Furthermore, for example, Japanese Patent Application Publication No. 2001-310458 discloses an apparatus capable of borderless recording and simultaneous recording onto both surfaces of a recording sheet. As one example of the apparatus, an apparatus is known in which an ink acceptance device and a wiping device are disposed on each side of the recording sheet and each ink acceptance device is disposed across a recording sheet from the wiping device. In this apparatus, the recording device, the ink receiving apparatus, and the wiping apparatus can reciprocate in a perpendicular direction with respect to the conveyance direction.
In an inkjet apparatus for double-side recording, in order to achieve both high-speed recording and double-side recording, it is important to shorten the recording time by recording on both sides of a recording medium substantially simultaneously, and to shorten the conveyance time by shortening the conveyance path for the recording medium.
Furthermore, in these days, there are requirements for double-side recording onto various types of recording media, and in particular, there is a requirement to perform double-side recording onto rigid plate-shaped recording media that are thick, hard, heavy, and unbendable, such as glass plates, iron plates, cardboard sheets, wooden sheets, and the like. In addition, desirably, recording can be adapted to a plurality of thicknesses.
However, the double-side recording technology described above has a possibility that it cannot meet requirements of these kinds.
For example, in the technology described in Japanese Patent Application Publication No. 2003-182094, images can be simultaneously recorded onto both surfaces of a recording medium. However, since the recording medium is conveyed in a downward perpendicular direction with respect to the recording head, it is difficult to convey the recording medium stably if the recording medium is heavy. Furthermore, the distances between the recording heads and the recording surface are almost uniform, and the rollers of the conveyance device have no mechanism for adapting to change in the thickness of the recording medium. Hence, it is difficult to adapt to a plurality of types of recording media having different thicknesses.
Moreover, in the apparatus described in Japanese Patent Application Publication No. 2004-181871, since it is difficult to bend rigid plate-shaped recording media as described above, such a medium cannot be reversed with the reversal mechanism (switch back mechanism). Hence, it is difficult for the apparatus to perform the double-side recording onto the rigid plate-shaped bodies as described above. Furthermore, it is difficult to adapt to a plurality of types of recording media having different thicknesses.
Moreover, in the apparatus described in Japanese Patent Application Publication No. 2004-216680, similarly, since it is difficult to bend rigid plate-shaped recording media as described above, it is difficult to perform the double-side printing. Furthermore, in this case, it is difficult to adapt it to a plurality of types of recording media having different thicknesses.
Moreover, in the apparatus described in Japanese Patent Application Publication No. 2001-310458, if ink is ejected onto the end sections of a recording medium or sections where no recording medium is present when the recording medium is thick, then the liquid droplets ejected from the head of which the ejection direction is the vertically upward direction, falls back onto and adheres to the nozzle surface, giving rise to ejection defects. Furthermore, even if an ink receiving apparatus is used for an apparatus that ejects ink horizontally, then it is difficult to gather the ink accurately in the ink receiving apparatus because the ink droplets drop under the effects of their own weight. As a result of that, soiling of the interior of the apparatus may occur, and consequently the quality of the recorded image may decline.
Moreover, if double-side recording is carried out while the recording medium is held vertically and conveyed in a horizontal direction, then the negative pressure balance at the ejection openings can be disrupted due to the arrangement of the print head. Hence, leakage of liquid from the ejection openings, loss of ejection stability, or the like may occur.